Stoichiometry Warm-up 5/2/11 H 2(g) + O 2(g)  H 2 O (g) How many moles of oxygen are needed to react with 3.7 moles hydrogen gas? How many moles of water can be produced from 12.5 g of oxygen? How many grams of hydrogen are needed to produce 67.0 grams of water?

Percent Yield 5/2/11 Actual yield X 100 theoretical yield

Percent Yield 5/2/11 What is the percent yield if 13.1 g CaO is actually and the theoretical yield is 15.2 g? 13.1 X 100 = %

Percent Yield 5/2/11 If 50.0 g of silicon dioxide is heated with excess of carbon, 27.9 g of silicon carbide is produced. SiO 2 (s) + 3C (s)  SiC (s) + 2CO (g) What is the percent yield?

Percent Yield 5/2/11 If 15.0 g of nitrogen reacts 15.0 g of hydrogen, 10.5 g of ammonia is produced. N 2 (g) + H 2 (g)  NH 3 (g) What is the percent yield in this reaction?

The Heat is on 5/4/11 warm-up Let’s finish test if not What are the 3 equations you need for heat? Look in chapter 17 What temperature does water freeze and ice melt? What temperature does water boil and steam condense?

Critical point – temp and pressure that distinction between gas and liquid stops Critical point – temp and pressure that distinction between gas and liquid stops Critical point for water Critical point for water o C at atm Critical point for CO 2 Critical point for CO 2 31 o C at 73 atm

Heating curve lab Procedure: Procedure: 1) With a partner scoop out enough ice to fill your beaker 2) Get a thermometer 3) Place thermometer in ice without it touching bottom of beaker, may have to use paperclip to balance on side 4) Make sure hot plate is on, do not touch. 5) Record initial temperature and every minute throughout the trial until water boils for 5 minutes. 6) Graph data with Temp on Y-axis and time on X

Heating curve lab write up Your lab report sheet should include: Your lab report sheet should include: 1) The purpose of the lab 2) A complete heating curve for your groups data 3) Construct a cooling curve of your data (#2 &3 on graph paper) 4) Draw the molecules at each of the different intervals of the process from solid to vapor. See pg 41 5) Explain what heat energy was doing at interval of no temp change. 6) Why is it important to constantly stir the water during the lab? 7) When was our system in physical equilibria throughout the lab?